The present invention is directed to a new and novel method of fabricating needles useful in the dispensing of plastic fasteners. The present invention is also directed to needles fabricated by said method.
Plastic fasteners of the type used to attach, for example; merchandising tags to articles of commerce are well-known in the art, as illustrated by the following commonly assigned patents: U.S. Pat. No. 3,103,666, issued Sep. 17, 1963; U.S. Pat. No. 4,121,487, Oct. 24, 1978; U.S. Pat. No. 4,456,161, issued Jun. 26, 1984; and U.S. Pat. No. 4,955,475, issued Sep. 11, 1990.
In many instances, the aforementioned plastic fasteners are fabricated in the form of continuously connected fastener stock, the fastener stock comprising a pair of elongated side members interconnected by a plurality of cross-links or filaments. Frequently, one side member comprises a plurality of T-bars joined together by severable connectors, and the other side member comprises a plurality of T-bars or paddles also joined together by severable connectors. Individual fasteners are usually dispensed from the fastener stock with the aid of a dispensing tool. Such dispensing tools typically include a needle through which the T-bar of a severed fastener is ejected into a desired article.
Such needles typically include a shank portion which has a relatively sharp tip to permit penetration of the desired article and a substantially cylindrical rear portion. The shank is hollow to permit the T-bar end of the fastener to pass therethrough and has a longitudinal slot to permit the filament of the fastener to extend therefrom as the T-bar end moves through the needle. The shank portion extends from a substantially cylindrical base having a central bore with an inner diameter equal to the inner diameter of the hollow shank. The base also has a longitudinal slot aligned with the slot in the shank. In needles which are removable from the dispensing tool, the base is provided with means for correctly positioning the needle within the tool and means for locking same into place.
Needles of the type described above are produced commercially using two different constructions. According to one construction, the base and shank are machined from a single piece of metal. This construction has high strength (due in part to the cross-sectional thickness of the needle), which is necessary for certain applications (see, e.g., the application discussed in commonly assigned U.S. Pat. No. 4,877,172, issued Oct. 31, 1989). However, as can readily be appreciated, the process of machining a single piece of metal into the required form is an arduous and time consuming task which results in a relatively expensive product.
According to the second construction, the needle comprises two separate pieces, a metal shank portion which is stamped from a flat sheet of metal and thereafter rolled into the desired configuration, and a plastic base portion which is molded around the end of the shank portion. This construction results in a needle which is considerably less expensive to manufacture than the all-metal, single-part first construction, but is not as thick as the first construction and is more susceptible to being damaged in use.